Secret telephone-exchange.



R. M. BEARD. SECRET TELEPHONE EXCHANGE. APPLMATION FILED MAY 2.1904. RBNEWBD SEPT. g4, 1914.

vPatend N QV. 17, 1914.

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[Dwi Meme/11 R. M. BEARD.' A SECRET TELEPHONE EXCHANGE.

APRLIOATION FILED MAY z, 1904. RENEWED SEPT. 24, 1914.

1,1 17,156. Patented Nov. 17, 1914.`

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nioi'iiinn M. BEARD, or NEW YoRicN. Y.

SECRET TELEPHONE-EXCHANGE.

Specification of Letters Patent.`

Application filed May 2, 1904, Serial No. 205,938. Renewed September 24, 1914;. Serial No. 863,396.

T all whom it may concern: l Beit known that I, RICHARD M. BnARD,-a citizen of the UnitedStates of America, and

resident of New York, in the county of Newv York and State of New York, have invented 'certain new and useful Improvements in Secret Telephone-Exchanges, oi' which the following is a specification.

My invention relates generally to telephone systems, and specifically to a secret system of telephonie communication, whereby, in a central exchange instalment, when any two subscribers lines are connected together Ain a circuit for talking, no central exchange operator or other party at the exchange `is able through any manipulation of his telephone apparatus or switching'devices to listen in or to connect any third V subscriber in the said circuit, while the two subscribers are in communication." No complicated or unusualmechanism is needed in my-system, privacy being secured. through the disposition of the circuits'.

My invention relates more particularly to a central exchange instalment employing a cordless switch board, such aswitchboard being commonly called' a desk monitor.

Thevobject of afcordless switch board is to eliminatea serious and frequent trouble due to broken connections in flexible cords incl- However the' cordless dental to their use. switch board, on account of its limited capacity, is not adapted to large c entral exchanges, but is' commonly used for private branch exchange work.

My present invention is of the same gen'- i eral character, and has the same underlying principles, as' disclosed in my U. S. Letters Patent Number 767,033, issued August 9, .1904; the particularA construction theredescribed being applicable to the cord switch board-the more common of .the two-while the details ot the presentconstruction apply more particularly to thecordless or desk monitorforin of switch board. This later or present application contains the broader claims.' Both the cord and-cordless switchboards arev sometimes usedfor practically the same work, namely, connecting together i any two of a number of subscribers lines; andboth have operators telephone circuits 'and listening keys for the operator'.

Inusing the desk monitor board-for private branch exchanges, the vobgect isto give -throwing the corresponding keys to connect both together, on any one of veditl'erentpairs of lbus wires` It is also provided that the operator may connect anytwo of'the extension instruments together, by operating the two keys respectively corresponding to connect them together on any one of the five buses. W hen t'Wo extensions are connected to'- gether, a common battery is supplied directly to the bus wires by a feed from a main central exchange,.but when an extension is connected with a trunk, no talking battery is, or need be, supplied-at the monitor, for the battery is then supplied at the main central.

The construct-ion thus far described is old,

f but is necessary to a proper understanding oiz' my invention.

Generally, without regard to the exact scope, my invention consists of subscribers lines, trunk jlines, switching keys and a group of wiring for connecting together any twosubscribers lines or for connecting any subscribers line with a trunk line, and switching apparatuslocated at the exchange instalment by which the exchange operator is prevented from having talking or listening connection simultaneouslywith any two connected subscribers. I A

In the prior art, .listening keys are vconnected directly with pairs of bus Wires, and

with them, the monitor board operatonmay vlisten to any'or all conversationsatywill,

because he can listen in onj'any pair of bus wires connectingV any two oi* more sub.-

scribers lines. In my invention, each trunk Patented Nov. 17, 1914.

line-and each subscribers line entering the exchange passes through corresponding individual listening keys, to each oi?v which the operators telephone circuit is multipled, and mechanism is providedvwhereby when 'any listening key is thrown into lislteningposition i it is automatically inain.

tained disconnected from the bus wires and atthe same time the operators circuit is opened to every listening key occurring .after it in the multiple. f, All fof the other apparatus'and` circuits arearranged in the y circuit and O is the othervside, The wiresA manner usually employed in cordless exchange instalments.

F or further explanation, reference will now be had to the accompanying drawings, The desk monitor board there shown in diagram is of the regulation size, and so far as not necessarily modiiied by the addition of my invention, is otthe regular design commonly employed wherever cordless switchboards are used.

Figure 1 is a diagram showing my invention applied to a private branch exchange instalment using a cordless switch board. Fig. Q is a diagram showing a portion of what is shown in Fig. 1 on a greatly enlarged scale.

E1, E, E3, E4, E5,.E6 and E7 each represent one side of respective subscribers lines, or extensions, of which E1, E, E, E, E, E` and E" represent the other sides respectively; and T1, T2, T3, and T1, T2, T3, represent the opposite sides respectively of respective .trunk lines, which may connect to another exchange like that illustrated,

or to a main central exchange.

L1, L?, L8, L1, L5, L, L7, L8, L9 and L10 are listening keys, in eachof which one of the extention subscribers lines or one of the trunk lines terminates respectively.

YO is one side of the operators telephone OA and O are connected respectively to opposite sides of the key L1, and the wire O is connected to the next key Lzthrough the contacts 1 and 2, which are normally closed; the wires"O,'Ol are connected respectively to opposite sides of the key L1, and the wire O is connected to the next succeeding key.

La through the contacts 1a and 2a, which are normally closed; and so on alternately, themanner of connecting'the operators telei phone wires to the listening keys being to connect iirst one and then the other ofthern respectively to each succeeding key through a normally closed pair of contacts on the preceding key in the multiple. The vobject in having the wires O and O alternate with each other in passing through the normally closed contacts 1, 2 and la, 2a, and so on, is that the operators circuit may not be unbalanced by having the resistance of all these contacts on one side."y

s1 to 83 inclusive are double throw switch keys by means of which, with suitable wiring, any two subscribers telephones may be connected together, or any subscribers telephone may be connected with any one of the trunks.

b1, 7;1, 61,'62, b3, 1)3, b4 b and b5 b5 are pairs of bus wires each pair of which multiples to one side of one of the double throw switch keys in each one'of the series belonging to the respective extension lines,

and each pair of which has included in Series one side of one of the double throw Lirama switch keys belonging to each of the trunks.

rlhe bus wires are connected as ordinarily, to a common battery feed F F from` respective extensions, and which suppliesthe current for signaling on the extensions. the extra cam c, and the corresponding battery tap t t and retardation coil R', are for supplying talking battery to the opera' tors circuit for talking locally, a'. e., with one of the extensions. Thel local battery supply will not be required when the operator talks out on the trunks, and may then be disconnected by operating the cam c.

Now let it be assumed that a party desires to call and talk with another party to which he has no direct line, but with whom he can get a` connection vthrough the exchange shown, and let us suppose that the partys line is the one of which the line E1 E1 is the continuation, and proceed to trace the same. The wires E1 and E1 respectively connect to the springs 3 and 4 of the listening key L1 which springs are normally in contact with springs 5 and 6, from which wires connect each spring respectively to the springs 9 and 10 of the switch key s1. AThe springs 9 and 10 of the keyfrs1 are normally in contact respectively withsprings 11 andl 12, from which wires vvconnect respectively to springs 13 and 14. -Springs 13 and 14 are normally in contact respectively .with-,springs 15 and 16, fromwhich wires' connect each spring. respectively vto s1, the next switch key in the series belonging to the ,line E1 E1, and which has a similar arrangement of springs to the key s1, and which in turn is similarly connected by wires to sa, the remaining switch key in that series,

the inside contact springs of which are connected up with a signal receiving device S. Thus it is seen that the three switch keys s1, a2 and s3A are normally connected in series, through closed contacts thereon and on the listening key L1, with'the line E1 E1, and the switch keys s, v and s are similarly lconnected up with vthe line E2 E, and so on in like manner the corresponding switch keys are connected to each of the extension lines. The switch keys 822, S23, s, etc., however,^ for each trunk line, are connected thereto in multiple. When the operator receives the signal', he throws the listening key L1 into the position to listen on the line E1 v telephone circuit, and the operator is then in talking circuit with the party calling. As soon as the operator learns what subscriber the party calling wantsl to be connected with, he throws the switching key connected with the generator circuit and which corresponds with the number of the desired subscriber. Assuming that the call comes for the party having the line E2 E, to signal him, the operator throws the switch key .si4 in position to signal-on that line, in which position the wedge {wl is forced in between the springs 9%1 and 10a far enough to cause them to break contact with springs 11a and 12u and to make contact with springs 17a and 181 which are tapped respectively to G and G, the two sides of the circuit to the signaling generator, and then restores the key to the normal position. The operator may now connect the two subscribers together for talking on any pair of bus wires not in use, as indicated by the busy signals B. If the pair of buses b1 bg is used, then the switch keys s1 and s4 are employed to make the connection. To do this, the wedge w1 of the key s1 is forced in between the springs 13 and 14 far enough to cause them to break Contact with -springs 15 and 16 and to makecontact respectively with springs 19 and 20, and the wedge fwl of key S4 is forced in between the springs 13a and-1 4a far enough to cause them to break Contact with springs 15a and 16a and to nia-ke contact respectively with springs 19a and 20a.- The operator now throws the listening key L1 back Ato normal position, and the two parties are then connected together for talking.. When they have finished, as indicated by theclearing out of the signal B when both receivers are hung up, the switch keys s1 and s4 maybe restored to norma-l position. A similar connection may be likewise established between any two of the lines on any pair of bus wires by operating two of the respectively corresponding switch keys. If, after signaling, the operator desires to listen on line E2 E, he may do so by restoring the listening key L1 to normal position and throwing the key L2 into listening position in the same manner that the key 'L1 was operated. When A the key Z2 is in position to listen on line E2 The operator may listen upon any one of the 6 0 E2 the wedge w is forced in ,betweenthesprings 8a and 4e far enough to cause them to break contact with the springs 5'c1 and 6EL and to make contact with springs 7'a and 8a, thus placing the operators telephone wires O and O in'circuit respectively with E2 and EZ, the two sides of the subscribers line.

trunksin the same manner as upon an extension, anda trunk and an extension may be connected together for talking in the same way that two extensions'are so connected.' The wiring to the springs on the switch keys belonging to the `trunk lines is such that when a trunk is connected to va bus wire (for tal-king on an extension) the keys prevents the operator from -connecting two subscribers together over his telephone circuit, by throwingtwo listening keys to listening position at thel same time. For example, when the listening key L1 is thrown into position to listen o-n the line E1 and E, contact is broken between the springs 1 and' 2, which are otherwise in contact, thus openingthe wire O to the keyL2, and when the key L2 is thrown into positionto listen on the line E2 E, contact is broken between the springs la and 2a, which are otherwise in contact, thus opening the wire O to the key L3. Similar springs are installed in the operators circuit on every -erators telephone circuit to the listening listening key, and by tracing the connections, as illustrated, it will be seen that when any key is thrown into listening position,

one of the operators telephone wires is opened to every key occurring after it in the multiple. It' follows from the above that the operator can listen on but one line at a time.

My invention is shown and described in connection with certain w'ell known telev hone appliances,but other accessories may e made use of and the invention carried out vin different ways without departing from the scope thereof as set forth in the claims. Those versed in the art will readily understand that many of the' details of my system may be altered as conditions require in any special installation, absolute privacy to telephonic conversations being secured in any case.

The reason that the lines have been shown in the accompanying drawings as terminating in the listening keys instead of in the signaling keys, which is usual, is to keep the' novel features separate from that which -is old. It is only necessary that each one of any two subscribers lines; and `devices adapted to he operated to connect the operators telephone circuit to any one @t the subscribers lines, each of which devices, when so operated, simultaneously disconnects both the said operators circuit and the said subscribers line from any other connections previously established, whereby the operator can listen on but one subscribers line y j means for detachably connecting together 2. A telephone central exchange instalat a time.

ment consisting of the 'combination of an operators telephone-circuit; means for detachably and electrically connecting together any two subscribers lines; and llistening keys to each of which said operatorie circuit is multiplied, andV each key adapted, when intlistening position, to open any one sub-4 scribers line to all others, and to simultaneously connect the operators telephone circuit to the said one subscribersl line, whereby the operator is unable tolisten on any but the last named subscribers line.

3. A telephone central exchange instal-v ment consistingv of the combination of an operators telephone' circuit; meansfor detachably connecting together any two subscribers lines; listening keys to each of `which said o erators circuit is multi lied,-

and adapted when in listening .position to open any one subscribers line to all others,

and to simultaneously connect the operators'l tachably connecting together any two sub scribers" lines; listening keys to each of which said operators circuit is multiplied, and adapted when in listening position to open any one subscribers line to all others, and to simultaneously connect the operators telephone circuit to the said one subscribers line; and a normally closed pair'ofcontacts on each of said listening keys and through which one of the wires to the operators telephone is .connected to the succeeding listening key in the multiple.

5. A telephone central exchange instalment cor sisting of the combination of an operators telephone circuit; means for -detachably connecting together any two subscribers lines; listening keys to each of which said operators circuit is multiplied, and adapted when in listening position to open any one subscribers line to all others, and to simultaneously connect the operators telephone circuit to the said one subscribers line; a normally closed pair of contacts on. each of said listening keys and through joperators telephone circuit;

`means for detachably connecting together which oneA of the wires to the operators Itelephone is connected to the succeeding listening key in the multiple; and a device for opening said contacts whenever any said listening key is thrown to listening position. l

-6. A telephone central exch-ange instalment consisting of the combination of an operator-s telephone J .circuit connecting any two subscribers" lines; a listening key for each subscribers line and to each of which said listening keys said operators telephone circuit is multipled, one pair of the terminals of each of said listening keys being normally connected to a subscribers line, one pair to said connecting means., and the remaining pair t0 the operators telephone-circuit. l

7. A telephone central exchange instalment consisting of the; combination .of an any two subscribers lines; a listening key for each subscribers line and to each of which said listening keys said operators telephone circuit is multipled, onepair of the terminals of each of said listening keys being normally connected to a subscribers line, one pair to said connecting means, and

the remaining pair to the operatorstelephone circuit; and a wedge for each listening key for controlling the connections of all of the said terminals thereof, and operating to connect the first named pair of terminals with either the one pair or the other of the other two pairs. 1

8. A telephone' central exchange instalment consisting of the combination of Vanl operators telephone circuit," connecting means for detachably connecting together any two subscribers lines; a listening key fon"each subscribers line and to each of which said listening keys said operators telephone circuit is multipled, one pair of Vthe terminals of each of said 'listening keys being connected to a subscribers line, one pair to sald connectmg means, and the reconnecting maining p air to the operators telephone circuit; and mechanism adapted when any key is thrown into listening position to open one side of the operators telephone circuit to every one of said listening keys occurring after it in the multiple.

9. In a telephone system, means including devices controlled by the operator for estab- -lishing a plurality of talking circuits between diferent subscribers simultaneously, meansoperated when any device is actuated to connect the operator witha talking circuit, for insuring the interruption of the operators connection with all the-other talking circuits, and means for additionally insuring the interruption of theoperators cnnection from any particular talking circuit which mil '40 stalment, the combination of subscribers can possibly be established at any time between the subscribers when such circuit is completed between two subscribers. i

10. In a telephone system, means including operators keys for establishing. a plurality 4of talking circuits between 4diierent subscribers simultaneously, means operated. when any key' is displaced to connect the operator with a talking circuit, for insuring la the interruption of the operators connection with allth'e other talking circuits, and means for additionallyinsuring the interruption vof the operators connection from any particular talking circuit which can possibly be es'- tablished at any time between the subscribers when such circuit ,is completed between two subscribers. 11. In a telephone central exchange instalment, the combination of subscribers lines electrically connected together through Y the exchange, an operatorstelephone circuit, and means adapted to be operated. to connect said circuit to any one of said lines,

v which said means, when so operated, .simultaneously disconnects said circuit and said any one of said lines from any .other connec- Vtions previouslyestablished. j`

'12. 'In a telephone `central exchange instalment, the combination of subscribers lines electrically connected together through the exchange, an operators telephone circuit, means adapted to be operated to connect said circuit to any one of said lines, and devices controlled bysaid means, which,

when said means is so operated, simultaneously disconnect said circuit'and said' any one of said lines from any other connections previously established. l v p 13. In a telephone central exchange in lines, an operators telephone circuit, means for connecting together any two of said lines through the exchange of said instalment, a listening key for each said line, and contact springs governed by said listening keys for electrically connecting said circuit to either one of said lines but only'while said one line is disconnected from all other lines. 14. Ina telephone central exchange instalment, the combination of subscribers lines electricallyconnected together through the exchange, an operators telephone circuit, and listening keys adapted to be operated to connect said circuit tov any one of said lines, which said listening keys, when so operated,

simultaneously disconnect said circuit and said any one of said lines from any other connections previously established.

15. In a telephone central exchange instalment, the combina-tion of` subscribers lines electrically connected together through the exchange, an operators telephone circuit, listening keys adapted to be operated to connect said circuit to any one of said lines, and

'$5 contact springs carried by said listening fai-17,1156' 3 and 4.

keys which, when said listening keys are sol operated, simultaneously disconnect said circuit vand said any one' f said lines from any'other connections previously established.

16. In a telephone central exchange instalment, the combination of subscribers lines electrically connected together through the` exchange, an operator-s telephonel circuit,v listening .key wedges, and con-l tact springs controlled by -said listening key wedges, which, when said wedges are operated, simultaneously disconnect said circuiit and said any one of said lines from any other connections previously established andV connect said circuit to one of said lines.

17. In a telephone central exchange instalment, the combination "of subscribers lines, an operators telephonev circuit, lis- .tening keys for connecting any one of said lines to said circuit, and contact springs carried and controlled by said listening keys for invariably maintaining said circuit'disconnected from all the' remaining lines during the time that said any one line isconnected to said circuit.

18. In a telephone system, means including operators keys for vestablishing a plurality of talking' circuitsv between different subscribers simultaneously, and means operated,`when any key is displaced to connect the operator -with a talking circuit, for insuring the'interruption of the operators connection with all the other talking circuits.

19.' In a telephone central exchange instalment, the combination of subscribers lines, an operators circuit having contacts 1 and 2, and contact springs 3 and 4 for connecting said circuit to one of said lines for controlling the separation of contacts stalment, the combination 'of subscribers lines, an operators circuit, contact springs 3 and 4 for connecting said circuit to one of said lines, and for-simultaneously disconnecting said circuit :trom' another subscribers line,.contact springs 7 and 8 ,permanently connected to said circuit, and contact springs 5 and 6 adapted to be GQ11- nected to said another subscribersline, and normally in contact with the contact springs 21. In a cordless telephone central exchange instalment, the combination of a listening'key having a wedge, a subscribers line spring contacts bearing thereon andv movable thereby, an operators circuit contacts in the path of the first named Acontacts, contacts 5 and -6 normally in contactwith the rst named contacts, and switchling keys for connecting said contacts 5 and 6 with another subscribers -line iso ` 22. In a telephone central exchange instalment, the combination of a listening key having a wedge, a subscribers line spring contacts bearing thereon and movable thereby, an operatorsv circuit contacts in the path of the first named contacts, contacts and 6 normally in contact with the rst named contacts, switching keys .for connecting said contacts 5 and 6 with another subscribers line, and normally closed contacts l and 2 .in series with the operators circuit and controlled by the first named contacts. n

.23. In a telephone central exchange instalment, the combination of subscribers lines, listening keys each having a-pair of contacts normally open to the respective lines, and an operators circuit. to which said contacts are multipled, said keys having spring contacts preventing said open contacts .of any key vfrom being connected to more than one of said subscribers lines ata time. 1

24. In a telephone central exchange instalment, the combination of a subscribers line, a listening key, a switching key, a

second switching key, a second listening l u n u key, land, a second subscribers line, all 1n a 'closed electric series circuit, 1n the (order named, and an operators circuit, the contact springs of said-listening keys being such that said series circuit is broken between said lines, upon actuating one of said circuit, and listening keys, the wedge of listening keys'to connect said operators circuit to one of said lines.

25.'In a telephone central exchange instalment, the combination of a subscribers line, a listening key, a switching key, a second switching key, a second listening key, and a second subscribers line, all. in a closed electric series circuit, in the order named, and an operators circuit, the contact springs of said listening keys being such that said series circuit is broken between said lines upon actuating one f said listening keys to connect said operators circuit to one of said lines cuit and adapted to connect said circuit to one of said lines when a certain one listen-VY ing key-is out of the normal contacts being disconnected.

27. In a telephone central exchange instalment, the combination of an operators phase, the first `more than one key at a time.

29. In a telephone central exchange instalment, the combination of listening keys an operators circuit multipled to each o said listening keys, and means adapted, when any key is thrown into listening position, to open the said operators circuit to every one of said listening keys occurring after it in the multiple. i

30. In a telephone central exchange instalment, the combination of listening keys, an operators circuit normally connected to said keys, and means automatically preventing more than one said listening key being connected to said circuit in lisiflqiing phase at a time.

`31.' In a telephone central exchange instalment, the combination oi .listening keys. an operators circuit multipled to each of said keys, 'and means adapted, when' any two said '-keys are thrown into listeningv 'i phase at any one time, to automatically open the said operators circuit between the two said keys. l

32. In a telephone central exchange inl .stalment, the combination of listening keys,

an operators circuit multipled to each of said keys, and a normally closed pair of contacts on each of said listening keys and through which one side of the operators .circuit is connected to the next succeeding listening key in the muitiple.

33. In a ,telephone centralvxchnge instalment, the 'combination of listening keys,

an operators circuit multipled to each of said keys, a normally closed pair of contacts on each ofI said listening keys and through which one side of the operators circuit is connected to the next succeeding listening key in the multiple, and means operating to automatically open said contacts nwhenever any said listening key is thrown to listening position.

34:. In a telephone central exchange instalment, the combination of subscribers lines, a listening key for each. subscribers line, an operators circuit multipled to each of said keys, and means adapted, when any key is thrown into listening position, to open the said operators circuit to every one of said listening` keys occurring after it'in the multiple. f

35. In a telephone central exchange instalment, the combination toi? subscribers lines, a listening key .for 'each subscribers line, an operators circuit, `and means .op-

los

erating automaticallyte prevent 1,110.17@ than one of said listening keys being connected;

in listeningphase to said circuit at any one time.

36. In a telephone central exchange instalment, the combination of subscribers lines, a listening key for each subscribers line, an operators circuit multipled to each of said keys, and means adapted, when any two said keys are thrown into listening phase at any one time, to automatically open the said operators circuit between the two said keys.

37. In a telephone central exchange insta-hnent, the combination ofV subscribers lines, a listening key, for each subscribers line, an operators circuit multipled to each ofv said keys, a normally closed pair oi contacts on each of said listening keys and through which one side of the operatorscircuit s connected to the next succeeding listening key in the multiple, and means operating to automatically open said contacts whenever any said listening key is thrown to listening position.

y 23S-.iA telephone central exchangeiinstalment consisting of the combination of an operators telephone circuit; means for detachably vand electrically connecting together any twosubscribers lines; andylistening keys adapted, when 'm listening position to open any -one subscribers line to all others, and to simultaneously. connect the operators telephone circuit to the said one subscribers line, whereby the operator is unable to listen on any but the last named subscribers line.

39. In a telephone system, subscribers circuit and -said one line Jfrom all other hnes.

40. Ina telephone central exchange instalment, an operators telephone circuit, means connecting subscribers lines together through the exchange in pairs, and devices, controlled by said means, which may at any time be operated simultaneously with said means to disconnect any pair of said lines from each other and to connect said operators circuit with either the one or the other of the said any pair of said lines.

. 4l. In a telephone system the combinationof an' operators' telephone circuit; means for electrically connecting together any two subscribers lines, listening keys for each of said lines, said keys being adapted when 'in operative position to open any one' subscribers line to a-plurality of the others, and to soconnect the operators telephone circuit that the operator is unable to listen on any but the line of'the last mentioned subscriber.'

Y In testimony whereof I have hereunto subscribed my name this thirtieth day of April, 1904.

RICHARD BEARD. 

